Environment-friendly production method for continuously producing bromo-polycarbonate

Abstract

The invention provides an environment-friendly production method for continuously producing brominated polycarbonate, and relates to the field of brominated polycarbonate. The environment-friendly production method for continuously producing brominated polycarbonate comprises the following steps: first photocatalytic decomposition, second photocatalytic decomposition, microchannel polymerization reaction, purification and post-treatment. According to the environment-friendly production method for continuously producing the bromo-polycarbonate, the problems of high catalyst cost, short catalyst service life, easiness in generation of byproducts, low reaction efficiency, tedious process flow and poor safety in the existing industrial production method of the bromo-polycarbonate can be effectively solved; the high-precision control on the molecular weight size, molecular weight distribution and particle size distribution of the prepared bromo-polycarbonate is realized.

Description

Technical Field

[0001] The invention relates to the field of brominated polycarbonate, in particular to an environmentally friendly production method for continuously producing brominated polycarbonate. Background Art

[0002] Brominated polycarbonate is a highly efficient and environmentally friendly bromine-based flame retardant. Its molecular chain contains a brominated bisphenol A carbonate structure (such as tetrabromobisphenol A copolymer), which gives it excellent flame retardant properties. Bromine elements can decompose at high temperatures to produce free radicals, blocking the combustion chain reaction, thereby achieving a flame retardant effect. Compared with chlorinated products, brominated polycarbonate has stronger heat resistance, a softening point of up to 350-370°C, and higher flame retardant efficiency. Brominated polycarbonate is mainly used in the flame retardant treatment of thermoplastics that do not require high transparency, such as polyester materials, engineering plastics, electronic and electrical materials, etc.

[0003] Chinese patent CN118056857A discloses a method for continuous production of polycarbonate and polycarbonate, which firstly conducts interfacial polymerization reaction of an alkaline aqueous solution containing sodium bisphenol and an organic solution containing phosgene to obtain a photochemical reaction liquid containing polycarbonate oligomers; wherein the molecular chain of the polycarbonate oligomer can be ionized at the interface of the alkaline photochemical reaction liquid to obtain a polymer chain containing phenol oxygen anions, which is then adsorbed on the surface of water droplets to form a macromolecular surfactant to stabilize the emulsion. Subsequently, the photochemical reaction liquid containing the polycarbonate oligomer is placed in a three-stage dispersion device for three-stage dispersion, and a capping agent is added to the photochemical reaction liquid before each stage of dispersion to control the molecular weight of the polymer and obtain a dispersed emulsion in an oil-in-water state; in this process, the capping agent is added three times, and the capping effect of the capping agent is improved by three-stage dispersion. Finally, the dispersed emulsion obtained by the three-stage dispersion is subjected to polycondensation reaction to obtain a polycarbonate of a certain molecular weight. Although this patent can produce polycarbonate with low terminal hydroxyl content and yellowing resistance, its reaction efficiency is low, and the multiple batch addition of the end-capping agent will greatly increase the risk of phosgene leakage; at the same time, the molecular weight of the polycarbonate product produced is single and cannot be adjusted, and the process flexibility is low.

[0004] Chinese patent CN103848983B discloses a method for synthesizing brominated polycarbonate, which adopts a homogeneous method to produce brominated polycarbonate, reduces mass transfer resistance, and reduces reactant consumption; at the same time, it adopts a self-made composite catalyst to catalyze the reaction during the reaction; the byproduct hydrochloric acid produced during the reaction is extracted by slight negative pressure and absorbed by water to generate hydrochloric acid. Specifically, after the solvent toluene, the raw material triphosgene and the composite catalyst are mixed into a transparent solution, a toluene solution of tetrabromobisphenol A is dripped at a temperature of 50-70°C, the reaction time is controlled to be 3-6h, and then after end-capping, brominated polycarbonate is obtained. However, the risk of phosgene leakage is high during its preparation process, and the molecular weight of the brominated polycarbonate obtained is single, and it is impossible to effectively adjust the molecular weight of the product.

[0005] Chinese patent CN116425965B discloses a flame retardant copolymer polycarbonate and its preparation method, wherein the first feed liquid is mixed with bisphenol A sodium salt solution, and then introduced into a two-stage tubular reactor with phosgene solution for reaction for 45-300 seconds to obtain a second feed liquid; then, in a three-stage tubular reactor, the low molecular weight copolymer polycarbonate is subjected to end-capping reaction under the action of an end-capping agent. Although the patent can realize the continuous production of flame retardant copolymer polycarbonate, the halogen content of the flame retardant copolymer polycarbonate prepared by the patent can only reach 34.52% at most, and its reaction safety, environmental protection, and product molecular weight controllability need to be further improved.

[0006] Furthermore, the conventional industrial preparation method of brominated polycarbonate is as follows: (1) dissolving catalyst 4-dimethylaminopyridine in water to obtain a catalyst solution for standby use; (2) adding tetrabromobisphenol A, an organic solvent, triphosgene and water into a reaction container and stirring the mixture evenly; (3) adding the catalyst solution into the reaction container and stirring the mixture evenly; (4) dissolving sodium hydroxide and monohydric phenol in water to obtain a mixed solution, and then slowly dropping the mixed solution into the reaction container at a predetermined reaction temperature, stirring the mixture for reaction, and obtaining a reaction solution; (5) washing the reaction solution with alkali, allowing the mixture to stand for stratification, and collecting an organic layer; (6) washing the organic layer with acid, allowing the mixture to stand for stratification, and collecting an organic layer; (7) washing the organic layer with deionized water, allowing the mixture to stand for stratification, and collecting an organic layer; (8) evaporating and drying the organic layer to obtain brominated polycarbonate. It has the problems of high catalyst cost (about 200,000 yuan / ton), short catalyst life, easy to produce by-products, low reaction efficiency, complicated process flow and poor safety. At the same time, during the preparation process, phosgene will react with the end-capping agent to form small molecules, which makes it impossible to control the molecular weight, molecular weight distribution and particle size distribution of brominated polycarbonate with high precision. Summary of the invention

[0007] In order to solve the technical problems existing in the prior art, the present invention provides an environmentally friendly production method for continuously producing brominated polycarbonate, which can effectively overcome the problems of high catalyst cost, short catalyst life, easy generation of by-products, low reaction efficiency, complicated process flow and poor safety existing in the existing industrial production method of brominated polycarbonate; and realize high-precision control of the molecular weight, molecular weight distribution and particle size distribution of the prepared brominated polycarbonate.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: An environmentally friendly production method for continuously producing brominated polycarbonate comprises the following steps: first photocatalytic decomposition, second photocatalytic decomposition, microchannel polymerization reaction, purification, and post-treatment; The first photocatalytic decomposition comprises continuously introducing the triphosgene solution into a reaction pipe of a first photocatalytic reactor, continuously performing the first photocatalytic decomposition in the presence of a first catalyst and under light conditions, and continuously obtaining a first photocatalytic decomposition product; The second photocatalytic decomposition comprises continuously introducing the aminocarbonyl compound solution into the reaction pipe of the second photocatalytic reactor, continuously performing the second photocatalytic decomposition in the presence of the second catalyst and under light conditions, and continuously obtaining the second photocatalytic decomposition product; In the microchannel polymerization reaction, the first photocatalytic decomposition product and the second photocatalytic decomposition product are premixed in a static mixer, and then continuously introduced into a micromixer for mixing to form a first stream of material; after the first stream of material and the second stream of material are mixed into a mixed solution, they are continuously introduced into a first microreactor for polymerization reaction to continuously obtain a polymerization reaction product; The second stream of material is a tetrabromobisphenol A mixed solution; The polymerization product is purified and post-treated to obtain brominated polycarbonate.

[0009] Furthermore, in the purification, the polymerization product and the washing liquid are simultaneously introduced into the second microreactor, and after washing and purification, the washed and purified product is continuously obtained; In the post-treatment, the washed and purified product is added to water, and after desolventizing by distillation, the solid is collected and dried to obtain brominated polycarbonate.

[0010] Furthermore, in the first photocatalytic decomposition, the feed rate of the triphosgene solution introduced into the first photocatalytic reactor is 3-20 mL / min, the illumination wavelength is 100-280 nm, the first photocatalytic decomposition temperature is controlled to be 15-36° C., and the material residence time is 3-16 min; The triphosgene solution is composed of triphosgene and a first solvent, wherein the concentration of triphosgene is 0.5-25 mol / L; the first solvent is at least one of the following: toluene, chloroform, dihalomethane, dihaloethane, carbon tetrahalide, chlorobenzene, and dichlorobenzene.

[0011] Preferably, in the first photocatalytic decomposition, the first catalyst is at least one of the following: titanium dioxide, nitrogen-doped titanium dioxide, zinc oxide, titanium nitride, carbon nitride, halogenated rare earth compounds, and tungstate compounds; The concentration of the first catalyst is 0.3-0.5 mg / mL.

[0012] Furthermore, in the second photocatalytic decomposition, the feed rate of the aminocarbonyl compound solution introduced into the second photocatalytic reactor is 0.5-10 mL / min, the illumination wavelength is 340-387 nm, the second photocatalytic decomposition temperature is controlled to be 30-50° C., and the material residence time is 1-12 min; The aminocarbonyl compound solution is composed of an aminocarbonyl compound and a second solvent, wherein the concentration of the aminocarbonyl compound is 1-25 mol / L; the aminocarbonyl compound is one of the following: amino acid, amide, urea; and the second solvent is at least one of the following: deionized water, methanol, ethanol.

[0013] Preferably, in the second photocatalytic decomposition, the second catalyst is at least one of the following: titanium dioxide, a noble metal catalyst, a transition metal catalyst, zinc oxide; The concentration of the second catalyst is 1-2.5 mg / mL.

[0014] Preferably, in the microchannel polymerization reaction, the feed rate of the mixed solution into the first microreactor is 5-20 g / min; the polymerization reaction temperature is controlled to be 30-40° C., and the material residence time is 1-16 min.

[0015] Preferably, the mass ratio of the first photocatalytic decomposition product to the second photocatalytic decomposition product in the first stream of material is 3-25:1; The second stream of materials consists of tetrabromobisphenol A, alkaline compound, end-capping agent, deionized water and organic solvent; The mass ratio of the first material to the second material in the mixed solution is 753-971:1578-1638.

[0016] Preferably, the alkaline compound is one of the following: sodium hydroxide, potassium hydroxide, aluminum hydroxide, ammonia water, potassium methoxide; The end-capping agent is phenol; The organic solvent is carbon tetrachloride or toluene; Preferably, the weight ratio of tetrabromobisphenol A, alkaline compound, end-capping agent, deionized water and organic solvent in the second stream of material is 333:65:20-80:580:580.

[0017] Preferably, in the purification, the washing and purification temperature is controlled to be 20-25°C, and the material residence time is 1-10min; The washing liquid is at least one of the following: deionized water, methanol, acetone; The volume ratio of the washing liquid to the polymerization product is 1:1-5.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The environmentally friendly production method for continuously producing brominated polycarbonate of the present invention comprises the following steps: continuously performing a first photocatalytic decomposition on triphosgene to obtain a first photocatalytic decomposition product; performing a second photocatalytic decomposition on an aminocarbonyl compound to obtain a second photocatalytic decomposition product; mixing the first photocatalytic decomposition product and the second photocatalytic decomposition product as a first stream of material, and subjecting the first stream of material (a mixed solution of tetrabromobisphenol A) to a microchannel polymerization reaction, followed by purification and post-treatment to obtain brominated polycarbonate; the various technical means cooperate with each other and work synergistically, and can effectively overcome the problems of high catalyst cost, short catalyst life, easy generation of by-products, low reaction efficiency, complicated process flow and poor safety existing in the existing industrial production method of brominated polycarbonate; and can achieve high-precision control of the molecular weight, molecular weight distribution and particle size distribution of the prepared brominated polycarbonate.

[0019] (2) The environmentally friendly method for continuously producing brominated polycarbonate of the present invention effectively solves the problems of high catalyst cost and short life. Combined with the specific process method of the present invention, it effectively improves the durability of the catalyst used, reduces the frequency of catalyst replacement (about once every 14 days of continuous production), and improves production efficiency. At the same time, the price of the catalyst used is much lower than that of existing catalysts, further reducing production costs.

[0020] (3) The environmentally friendly method for continuously producing brominated polycarbonate of the present invention can effectively reduce and remove by-products by adopting a continuous microchannel device for reaction and purification, thereby improving the control accuracy of the molecular weight and particle size of the brominated polycarbonate and improving the product performance of the brominated polycarbonate.

[0021] (4) The environmentally friendly production method for continuously producing brominated polycarbonate of the present invention has a simple process flow and is easy to control through specific process coordination. It can greatly shorten the reaction time, improve production efficiency, reduce production costs, and improve safety during the production process.

[0022] (5) The environmentally friendly method for continuously producing brominated polycarbonate of the present invention effectively solves the problem of low precision in controlling molecular weight and particle size in the existing preparation of brominated polycarbonate, realizes the set production of molecular weight of brominated polycarbonate products, and the molecular weight distribution (Mz / Mw) of the prepared brominated polycarbonate is in the range of 1-1.2. It can also realize high-precision control of the particle size of the brominated polycarbonate product, further expanding the application field of brominated polycarbonate products.

[0023] (6) The environmentally friendly method for continuously producing brominated polycarbonate of the present invention can effectively solve the problems of material leakage and odor in the existing intermittent preparation process of brominated polycarbonate, ensure the closed production process, effectively improve safety, and ensure the continuous preparation of brominated polycarbonate.

[0024] (7) The environmentally friendly production method of the present invention for continuously producing brominated polycarbonate simultaneously uses photocatalytic decomposition of triphosgene and photocatalytic decomposition of aminocarbonyl compounds. The decomposition is carried out in a safe, environmentally friendly, efficient and low-energy manner under a photocatalytic environment, effectively preventing phosgene leakage, reducing the phosgene content per unit reaction, and increasing the service life of the catalyst; at the same time, by using a static mixer for premixing, the reaction time is further reduced and the reaction efficiency is improved; further, a microreactor is used for continuous polymerization reaction to reduce the reaction equivalent and increase the reaction rate, and the molecular weight and particle size distribution of the brominated polycarbonate are accurately controlled by combining the amount of end-capping agent added and the process parameters related to the polymerization reaction; and a microreactor is used for washing to further increase the production rate and ensure the quality of the brominated polycarbonate product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the gel permeation chromatogram of the brominated polycarbonate prepared in Example 4.

[0026] Figure 2 This is the gel permeation chromatogram of the brominated polycarbonate prepared in Example 9.

[0027] Figure 3 The particle size distribution diagram of the brominated polycarbonate prepared in Examples 1 to 9. In the figure, Sample 1 to Sample 9 correspond to the brominated polycarbonate prepared in Examples 1 to 9, respectively. DETAILED DESCRIPTION

[0028] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] The embodiment of the present invention provides an environmentally friendly production method for continuously producing brominated polycarbonate, comprising the following steps: first photocatalytic decomposition, second photocatalytic decomposition, microchannel polymerization reaction, purification, and post-treatment.

[0031] The method for the first photocatalytic decomposition (i.e., continuous decomposition of triphosgene) is as follows: weigh a certain amount of triphosgene and a first solvent, add them into a blue-capped bottle, seal and shake to obtain a triphosgene solution with a concentration of 0.5-25 mol / L, and place it in a glove box; turn on the triphosgene solution feed pump, and continuously introduce the triphosgene solution into the reaction pipe of the first photocatalytic reactor at a feed rate of 3-20 mL / min; in the presence of the first catalyst and under a light environment, control the first photocatalytic decomposition temperature to be 15-36° C., the residence time of the triphosgene solution in the reaction pipe to be 3-16 min (preferably 5-8 min), and continuously perform photocatalytic decomposition of the triphosgene; and the obtained first photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0032] In the first photocatalytic decomposition, in order to initiate the free radical reaction of the photocatalytic decomposition of triphosgene, the wavelength of the light source used is 100-280nm, preferably 200-280nm (ie, ultraviolet C band).

[0033] The first solvent is at least one of the following: toluene, chloroform, dihalomethane, dihaloethane, carbon tetrahalide, chlorobenzene, dichlorobenzene; preferably toluene and carbon tetrachloride, and the weight ratio of toluene to carbon tetrachloride is 0.5-2:1.

[0034] The first catalyst is at least one of the following: titanium dioxide, nitrogen-doped titanium dioxide, zinc oxide, titanium nitride, carbon nitride, halogenated rare earth compounds, tungstate compounds; the first catalyst is preferably at least one of the following: titanium dioxide, zinc oxide, titanium nitride, cerium chloride.

[0035] The concentration of the first catalyst is 0.01-100 mg / mL, preferably 0.3-0.5 mg / mL.

[0036] The method for the second photocatalytic decomposition (i.e., continuous decomposition of aminocarbonyl compounds) is as follows: weigh a certain amount of aminocarbonyl compounds and a second solvent, add them into a blue-capped bottle, seal and shake to obtain an aminocarbonyl compound solution with a concentration of 1-25 mol / L; start the aminocarbonyl compound solution feed pump, and continuously introduce the aminocarbonyl compound solution into the reaction pipe of the second photocatalytic reactor at a feed rate of 0.5-10 mL / min; in the presence of the second catalyst and under light conditions, control the second photocatalytic decomposition temperature to 30-50°C, the residence time of the aminocarbonyl compound solution in the reaction pipe to 1-12 min (preferably 5-8 min), and continuously perform photocatalytic decomposition of the aminocarbonyl compounds; and the obtained second photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0037] In the second photocatalytic decomposition, in order to promote the decomposition of aminocarbonyl compounds, ultraviolet light is used to provide sufficient energy to break the chemical bonds in the aminocarbonyl compound molecules, and the wavelength of the light source used is 340-387nm.

[0038] The aminocarbonyl compound is one of the following: amino acid, amide, urea; preferably urea.

[0039] The second solvent is at least one of the following: deionized water, methanol, ethanol; preferably deionized water.

[0040] The second catalyst is at least one of the following: titanium dioxide, a noble metal (iridium Ir or ruthenium Ru) catalyst, a transition metal (cobalt, nickel or rhodium) catalyst, zinc oxide; preferably a transition metal catalyst; more preferably dicobalt octacarbonyl.

[0041] The concentration of the second catalyst is 0.01-100 mg / mL, preferably 1-2.5 mg / mL.

[0042] The method for the microchannel polymerization reaction is as follows: the first photocatalytic decomposition product and the second photocatalytic decomposition product are premixed in a static mixer, and then continuously introduced into a micromixer for mixing, and enter the mixing coil as the first stream of material; at the same time, a tetrabromobisphenol A mixed solution feed pump is turned on, and enters the mixing coil as the second stream of material; after the first stream of material and the second stream of material are mixed into a mixed solution in the mixing coil, they are continuously introduced into the first microreactor and its reaction coil at a feed rate of 5-20 g / min, the reaction temperature is controlled to be 30-40° C. (preferably 35-39° C.), the material residence time is 1-16 min (preferably 1-5 min), and after the polymerization reaction is carried out, a polymerization reaction product is continuously obtained.

[0043] In the microchannel polymerization reaction, the mass ratio of the first photocatalytic decomposition product to the second photocatalytic decomposition product in the first stream of material is 3-25:1, preferably 6-8:1.

[0044] The second stream of material (tetrabromobisphenol A mixed solution) is a mixture of tetrabromobisphenol A, alkaline compound, end-capping agent phenol, deionized water, and organic solvent. The alkaline compound is one of the following: sodium hydroxide, potassium hydroxide, aluminum hydroxide, ammonia water, potassium methoxide; preferably sodium hydroxide. The organic solvent is carbon tetrachloride or toluene; preferably toluene.

[0045] In the mixed solution, the mass ratio of the first material to the second material is 753-971:1578-1638.

[0046] The weight ratio of tetrabromobisphenol A, alkaline compound, end-capping agent phenol, deionized water and organic solvent in the second stream of material is 333:65:20-80:580:580.

[0047] The purification method is to continuously feed the polymerization product and the washing liquid into the second microreactor, control the washing and purification temperature to 20-25°C, and the material residence time to 1-10 minutes (preferably 3-5 minutes), and continuously obtain the washing and purification product after washing and purification.

[0048] In the purification, the washing liquid is at least one of the following: deionized water, methanol, and acetone.

[0049] The volume ratio of the washing liquid to the polymerization product is 1:1-5 (preferably 1:3).

[0050] The post-treatment method is to add the washed and purified product into water, heat it to boiling, maintain the temperature and perform distillation to desolventize the product, filter it and dry it to obtain the brominated polycarbonate.

[0051] The present invention is further described below in conjunction with some specific embodiments.

[0052] The main equipment used in each embodiment is as follows: Pump 1-constant flow pump (triphosgene solution feed pump), manufactured by Shanghai Tongtian Biotechnology Co., Ltd., made of stainless steel, model TBP5002S, flow range 0.1-50mL / min. The first photocatalytic reactor (triphosgene) used: size 220×112.7×3mm, light source wavelength 280nm (adjustable); the first solvent is used to calibrate the flow of the triphosgene solution feed pump (pump 1).

[0053] Pump 2-constant flow pump (aminocarbonyl compound solution feed pump), manufactured by Shanghai Tongtian Biotechnology Co., Ltd., made of stainless steel, model TBP1002S, flow range 0.1-10mL / min. The second photocatalytic reactor (aminocarbonyl compound) used: size 210×180×3mm, light source wavelength 365nm (adjustable); the second solvent is used to calibrate the flow of the aminocarbonyl compound solution feed pump (pump 2).

[0054] Pump 3-constant flow pump (tetrabromobisphenol A mixed solution feed pump), manufactured by Shanghai Tongtian Biotechnology Co., Ltd., made of stainless steel, model TBP5002S, flow range 0.1-50mL / min. The micro mixer uses a sieve plate (1, 0.5mm sieve hole), and a layer of raw tape is placed between the PTFE sheets for sealing; the reaction coil is a 1 / 8 PTFE tube, outer diameter × inner diameter = 3.17 × 1.58mm, length 17.5m; deionized water is used to calibrate the flow of the tetrabromobisphenol A mixed solution feed pump (pump 3).

[0055] The main raw material specifications used in each embodiment are as follows: Triphosgene, produced by Aladdin Reagent (Shanghai) Co., Ltd., purity> 99%; Urea, produced by Aladdin Reagent (Shanghai) Co., Ltd., purity ≥99.5%.

[0056] Toluene was used after being dried over molecular sieves to remove water.

[0057] Carbon tetrachloride is used after being dried over molecular sieves to remove water.

[0058] Example 1 This embodiment provides an environmentally friendly production method for continuously producing brominated polycarbonate, specifically: 1. First photocatalytic decomposition Weigh 75g of triphosgene and a first solvent (400g of toluene and 200g of carbon tetrachloride), add them to a blue-capped bottle, seal and shake to obtain a triphosgene solution, and then place it in a glove box; turn on the triphosgene solution feed pump, and continuously introduce the triphosgene solution into the reaction pipe of the first photocatalytic reactor at a feed rate of 5mL / min. In the presence of the first catalyst and under light conditions, control the first photocatalytic decomposition temperature to 23°C, and the residence time of the triphosgene solution in the reaction pipe to 7min, and continuously photocatalytically decompose the triphosgene; the obtained first photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0059] In order to initiate the free radical reaction of photocatalytic decomposition of triphosgene, the wavelength of the light source used is 280 nm.

[0060] The first catalyst is composed of titanium dioxide and zinc oxide, and the mass ratio of titanium dioxide to zinc oxide is 1:1; the concentration of the first catalyst is 0.3 mg / mL.

[0061] 2. Second photocatalytic decomposition Weigh aminocarbonyl compounds (6 g urea) and a second solvent (100 mL deionized water), add them into a blue-capped bottle, seal and shake to obtain a urea solution; turn on the aminocarbonyl compound solution feed pump, and continuously introduce the urea solution into the reaction pipe of the second photocatalytic reactor at a feed rate of 1 mL / min. In the presence of the second catalyst and under light conditions, control the second photocatalytic decomposition temperature to 38°C, and the residence time of the urea solution in the reaction pipe to 7 min, and continuously photocatalytically decompose urea; the obtained second photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0062] In order to promote the decomposition of aminocarbonyl compounds, ultraviolet light is used to provide sufficient energy to break the chemical bonds in the aminocarbonyl compound molecules, and the wavelength of the light source used is 365nm.

[0063] The second catalyst is dicobalt octacarbonyl; the concentration of the second catalyst is 2 mg / mL.

[0064] 3. Microchannel polymerization The first photocatalytic decomposition product and the second photocatalytic decomposition product are premixed in a static mixer, and then continuously introduced into a micromixer for mixing, and enter the mixing coil as the first stream of material; at the same time, the tetrabromobisphenol A mixed solution feed pump (pump 3) is turned on, and enters the mixing coil as the second stream of material; after the first stream of material and the second stream of material are mixed into a mixed solution in the mixing coil at a temperature of 18°C, they are continuously introduced into the first microreactor and its reaction coil at a feed rate of 9g / min, the reaction temperature is controlled to be 37°C, the material residence time is 117.58s, and after the polymerization reaction is carried out, the polymerization reaction product is continuously obtained.

[0065] The second stream of material (tetrabromobisphenol A mixed solution) consists of 333 g of tetrabromobisphenol A, 65 g of sodium hydroxide (alkaline compound), 80 g of end-capping agent phenol, 580 g of deionized water, and 580 g of toluene (organic solvent).

[0066] In the mixed solution, the mass ratio of the first stream of material to the second stream of material is 828:1638.

[0067] 4. Purification The polymerization product and deionized water (washing liquid) were continuously fed into the second microreactor, the washing and purification temperature was controlled to be 20°C, the material residence time was 5 minutes, and after washing and purification, the washing and purification product was continuously obtained.

[0068] The volume ratio of the washing liquid to the polymerization product is 1:3.

[0069] 5. Post-processing The washed and purified product is added to water, the temperature is raised to boiling, the product is precipitated after heat preservation and distillation, and the product is filtered and dried to obtain brominated polycarbonate.

[0070] Example 2 This embodiment provides an environmentally friendly production method for continuously producing brominated polycarbonate, specifically: 1. First photocatalytic decomposition Weigh 75g of triphosgene and the first solvent (300g of toluene and 300g of carbon tetrachloride), add them to a blue-capped bottle, seal and shake to obtain a triphosgene solution, and then place it in a glove box; turn on the triphosgene solution feed pump, and continuously introduce the triphosgene solution into the reaction pipe of the first photocatalytic reactor at a feed rate of 5mL / min. In the presence of the first catalyst and under light conditions, the first photocatalytic decomposition temperature is controlled to be 18°C, the residence time of the triphosgene solution in the reaction pipe is 8min, and the triphosgene is continuously photocatalytically decomposed; the obtained first photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0071] In order to initiate the free radical reaction of photocatalytic decomposition of triphosgene, the wavelength of the light source used is 280 nm.

[0072] The first catalyst is titanium dioxide; the concentration of the first catalyst is 0.4 mg / mL.

[0073] 2. Second photocatalytic decomposition Weigh aminocarbonyl compounds (6 g urea) and a second solvent (100 mL deionized water), add them into a blue-capped bottle, seal and shake to obtain a urea solution; turn on the aminocarbonyl compound solution feed pump, and continuously introduce the urea solution into the reaction pipe of the second photocatalytic reactor at a feed rate of 1 mL / min. In the presence of the second catalyst and under light conditions, control the second photocatalytic decomposition temperature to 32°C, and the residence time of the urea solution in the reaction pipe to 8 min, and continuously photocatalytically decompose urea; the obtained second photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0074] In order to promote the decomposition of aminocarbonyl compounds, ultraviolet light is used to provide sufficient energy to break the chemical bonds in the aminocarbonyl compound molecules, and the wavelength of the light source used is 365nm.

[0075] The second catalyst is dicobalt octacarbonyl; the concentration of the second catalyst is 1.2 mg / mL.

[0076] 3. Microchannel polymerization The first photocatalytic decomposition product and the second photocatalytic decomposition product are premixed in a static mixer, and then continuously introduced into a micromixer for mixing, and enter the mixing coil as the first stream of material; at the same time, the tetrabromobisphenol A mixed solution feed pump (pump 3) is turned on, and enters the mixing coil as the second stream of material; after the first stream of material and the second stream of material are mixed into a mixed solution in the mixing coil at a temperature of 18°C, they are continuously introduced into the first microreactor and its reaction coil at a feed rate of 9g / min, the reaction temperature is controlled to be 37°C, the material residence time is 117.58s, and after the polymerization reaction is carried out, the polymerization reaction product is continuously obtained.

[0077] The second stream of material (tetrabromobisphenol A mixed solution) consists of 333 g of tetrabromobisphenol A, 65 g of sodium hydroxide (alkaline compound), 80 g of end-capping agent phenol, 580 g of deionized water, and 580 g of toluene (organic solvent).

[0078] In the mixed solution, the mass ratio of the first stream of material to the second stream of material is 828:1638.

[0079] 4. Purification The polymerization product and deionized water (washing liquid) were continuously fed into the second microreactor, the washing and purification temperature was controlled to be 22° C., the material residence time was 4 min, and after washing and purification, the washing and purification product was continuously obtained.

[0080] The volume ratio of the washing liquid to the polymerization product is 1:2.5.

[0081] 5. Post-processing The washed and purified product is added to water, the temperature is raised to boiling, the product is precipitated after heat preservation and distillation, and the product is filtered and dried to obtain brominated polycarbonate.

[0082] Example 3 This embodiment provides an environmentally friendly production method for continuously producing brominated polycarbonate, specifically: 1. First photocatalytic decomposition Weigh 75g of triphosgene and a first solvent (200g of toluene and 400g of carbon tetrachloride), add them to a blue-capped bottle, seal and shake to obtain a triphosgene solution, and then place it in a glove box; turn on the triphosgene solution feed pump, and continuously introduce the triphosgene solution into the reaction pipe of the first photocatalytic reactor at a feed rate of 5mL / min. In the presence of the first catalyst and under light conditions, control the first photocatalytic decomposition temperature to 30°C, the residence time of the triphosgene solution in the reaction pipe to 5min, and continuously photocatalytically decompose the triphosgene; the obtained first photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0083] In order to initiate the free radical reaction of photocatalytic decomposition of triphosgene, the wavelength of the light source used is 280 nm.

[0084] The first catalyst is zinc oxide; the concentration of the first catalyst is 0.5 mg / mL.

[0085] 2. Second photocatalytic decomposition Weigh aminocarbonyl compounds (6 g urea) and a second solvent (100 mL deionized water), add them into a blue-capped bottle, seal and shake to obtain a urea solution; turn on the aminocarbonyl compound solution feed pump, and continuously introduce the urea solution into the reaction pipe of the second photocatalytic reactor at a feed rate of 1 mL / min. In the presence of the second catalyst and under light conditions, control the second photocatalytic decomposition temperature to 45°C, and the residence time of the urea solution in the reaction pipe to 5 min, and continuously photocatalytically decompose urea; the obtained second photocatalytic decomposition product is continuously introduced into the micromixer through a static mixer.

[0086] In order to promote the decomposition of aminocarbonyl compounds, ultraviolet light is used to provide sufficient energy to break the chemical bonds in the aminocarbonyl compound molecules, and the wavelength of the light source used is 365nm.

[0087] The second catalyst is dicobalt octacarbonyl; the concentration of the second catalyst is 2.5 mg / mL.

[0088] 3. Microchannel polymerization The first photocatalytic decomposition product and the second photocatalytic decomposition product are premixed in a static mixer, and then continuously introduced into a micromixer for mixing, and enter the mixing coil as the first stream of material; at the same time, the tetrabromobisphenol A mixed solution feed pump (pump 3) is turned on, and enters the mixing coil as the second stream of material; after the first stream of material and the second stream of material are mixed into a mixed solution in the mixing coil at a temperature of 18°C, they are continuously introduced into the first microreactor and its reaction coil at a feed rate of 9g / min, the reaction temperature is controlled to be 37°C, the material residence time is 117.58s, and after the polymerization reaction is carried out, the polymerization reaction product is continuously obtained.

[0089] The second stream of material (tetrabromobisphenol A mixed solution) consists of 333 g of tetrabromobisphenol A, 65 g of sodium hydroxide (alkaline compound), 80 g of end-capping agent phenol, 580 g of deionized water, and 580 g of toluene (organic solvent).

[0090] In the mixed solution, the mass ratio of the first stream of material to the second stream of material is 828:1638.

[0091] 4. Purification The polymerization product and deionized water (washing liquid) were continuously fed into the second microreactor, the washing and purification temperature was controlled to be 25°C, the material residence time was 3 minutes, and after washing and purification, the washing and purification product was continuously obtained.

[0092] The volume ratio of the washing liquid to the polymerization product is 1:2.

[0093] 5. Post-processing The washed and purified product is added to water, the temperature is raised to boiling, the product is precipitated after heat preservation and distillation, and the product is filtered and dried to obtain brominated polycarbonate.

[0094] The molecular weight and molecular weight distribution of the brominated polycarbonate obtained in Examples 1-3 were tested respectively, and the specific test results are shown in the following table:

[0095] Example 4 This embodiment adopts the technical solution of embodiment 1, and the following changes are made: (1) the mass of the end-capping agent phenol in the second stream of material in the microchannel polymerization step is changed to 60 g. (2) the material residence time in the microchannel polymerization step is changed to 156.77 s.

[0096] like Figure 1 From the gel permeation chromatogram of the brominated polycarbonate prepared in Example 4, it can be seen that the molecular weight distribution of the brominated polycarbonate prepared therefrom is narrow and concentrated. Example 5

[0097] This embodiment adopts the technical solution of embodiment 1, and the following changes are made: (1) the mass of the end-capping agent phenol in the second stream of material in the microchannel polymerization step is changed to 40 g. (2) the material residence time in the microchannel polymerization step is changed to 156.77 s. Example 6

[0098] This embodiment adopts the technical solution of embodiment 1, and the following changes are made: (1) the mass of the end-capping agent phenol in the second stream of material in the microchannel polymerization step is changed to 20 g. (2) the material residence time in the microchannel polymerization step is changed to 156.77 s.

[0099] The molecular weight and molecular weight distribution of the brominated polycarbonates obtained in Examples 4-6 were tested respectively, and the specific test results are shown in the following table:

[0100] Example 7 This embodiment adopts the technical solution of Embodiment 1, with the following changes: the material residence time in the microchannel polymerization reaction step is changed to 78.39 s. Example 8

[0101] This embodiment adopts the technical solution of Embodiment 1, with the following changes: the material residence time in the microchannel polymerization reaction step is changed to 156.77s. Example 9

[0102] This embodiment adopts the technical solution of Embodiment 1, with the following changes: the material residence time in the microchannel polymerization reaction step is changed to 235.16s.

[0103] like Figure 2 From the gel permeation chromatogram of the brominated polycarbonate prepared in Example 9, it can be seen that the molecular weight distribution of the brominated polycarbonate prepared therefrom is narrow and concentrated.

[0104] The molecular weight and molecular weight distribution of the brominated polycarbonates obtained in Examples 7-9 were tested respectively, and the specific test results are shown in the following table:

[0105] Furthermore, the particle size and particle size distribution of the brominated polycarbonate obtained in Examples 1-9 were tested respectively. The specific test results are as follows: Figure 3 As shown, it can be seen that the particle size distribution of the brominated polycarbonate prepared in each embodiment is concentrated; the environmentally friendly production method for continuously producing brominated polycarbonate can achieve high-precision control of the molecular weight, molecular weight distribution and particle size distribution of the prepared brominated polycarbonate.

[0106] It can be seen that the environmentally friendly production method for continuously producing brominated polycarbonate of the present invention continuously performs a first photocatalytic decomposition on triphosgene to obtain a first photocatalytic decomposition product; performs a second photocatalytic decomposition on an aminocarbonyl compound to obtain a second photocatalytic decomposition product; the first photocatalytic decomposition product and the second photocatalytic decomposition product are mixed as a first stream of material, and after a microchannel polymerization reaction with a second stream of material (a mixed solution of tetrabromobisphenol A), the brominated polycarbonate is obtained through purification and post-treatment; various technical means cooperate and act synergistically with each other, and photocatalytic decomposition of triphosgene and photocatalytic decomposition of aminocarbonyl compounds are simultaneously adopted, and decomposition is carried out in a safe, environmentally friendly, efficient and low-energy manner under a photocatalytic environment, thereby effectively preventing phosgene leakage, reducing the phosgene content per unit reaction, and increasing the catalyst content. service life; at the same time, by using a static mixer for premixing, the reaction time is further reduced and the reaction efficiency is improved; further, a microreactor is used for continuous polymerization reaction to reduce the reaction equivalent, increase the reaction rate, and accurately control the molecular weight and particle size distribution of the brominated polycarbonate in combination with the amount of end-capping agent added and relevant process parameters of the polymerization reaction; and a microreactor is used for washing to further increase the production rate and ensure the quality of the brominated polycarbonate product; it can effectively overcome the problems of high catalyst cost, short catalyst life, easy to generate by-products, low reaction efficiency, complicated process flow and poor safety in the existing industrial production method of brominated polycarbonate; and realize high-precision control of the molecular weight, molecular weight distribution and particle size distribution of the prepared brominated polycarbonate.

[0107] Unless otherwise specified, all percentages used in the present invention are by mass.

[0108] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An environmentally friendly production method for continuously producing brominated polycarbonate, characterized in that: The method comprises the following steps: first photocatalytic decomposition, second photocatalytic decomposition, microchannel polymerization reaction, purification, and post-treatment; The first photocatalytic decomposition comprises continuously introducing the triphosgene solution into a reaction pipe of a first photocatalytic reactor, continuously performing the first photocatalytic decomposition in the presence of a first catalyst and under light conditions, and continuously obtaining a first photocatalytic decomposition product; The second photocatalytic decomposition comprises continuously introducing the aminocarbonyl compound solution into the reaction pipe of the second photocatalytic reactor, continuously performing the second photocatalytic decomposition in the presence of the second catalyst and under light conditions, and continuously obtaining the second photocatalytic decomposition product; In the microchannel polymerization reaction, the first photocatalytic decomposition product and the second photocatalytic decomposition product are premixed in a static mixer, and then continuously introduced into a micromixer for mixing to form a first stream of material; after the first stream of material and the second stream of material are mixed into a mixed solution, they are continuously introduced into a first microreactor for polymerization reaction to continuously obtain a polymerization reaction product; The second stream of material is a tetrabromobisphenol A mixed solution; The polymerization product is purified and post-treated to obtain brominated polycarbonate.

2. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: The purification comprises introducing the polymerization product and the washing liquid into the second microreactor at the same time, performing washing and purification, and continuously obtaining the washed and purified product; In the post-treatment, the washed and purified product is added to water, and after desolventizing by distillation, the solid is collected and dried to obtain brominated polycarbonate.

3. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: In the first photocatalytic decomposition, the feed rate of the triphosgene solution introduced into the first photocatalytic reactor is 3-20 mL / min, the illumination wavelength is 100-280 nm, the first photocatalytic decomposition temperature is controlled to be 15-36° C., and the material residence time is 3-16 min; The triphosgene solution is composed of triphosgene and a first solvent, wherein the concentration of triphosgene is 0.5-25 mol / L; the first solvent is at least one of the following: toluene, chloroform, dihalomethane, dihaloethane, carbon tetrahalide, chlorobenzene, and dichlorobenzene.

4. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: In the first photocatalytic decomposition, the first catalyst is at least one of the following: titanium dioxide, nitrogen-doped titanium dioxide, zinc oxide, titanium nitride, carbon nitride, halogenated rare earth compounds, and tungstate compounds; The concentration of the first catalyst is 0.3-0.5 mg / mL.

5. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: In the second photocatalytic decomposition, the feeding rate of the aminocarbonyl compound solution introduced into the second photocatalytic reactor is 0.5-10 mL / min, the illumination wavelength is 340-387 nm, the second photocatalytic decomposition temperature is controlled to be 30-50° C., and the material residence time is 1-12 min; The aminocarbonyl compound solution is composed of an aminocarbonyl compound and a second solvent, wherein the concentration of the aminocarbonyl compound is 1-25 mol / L; the aminocarbonyl compound is one of the following: amino acid, amide, urea; and the second solvent is at least one of the following: deionized water, methanol, ethanol.

6. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: In the second photocatalytic decomposition, the second catalyst is at least one of the following: titanium dioxide, a noble metal catalyst, a transition metal catalyst, zinc oxide; The concentration of the second catalyst is 1-2.5 mg / mL.

7. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: In the microchannel polymerization reaction, the feed rate of the mixed solution into the first microreactor is 5-20 g / min; the polymerization reaction temperature is controlled to be 30-40° C., and the material residence time is 1-16 min.

8. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 1, characterized in that: In the microchannel polymerization reaction, the mass ratio of the first photocatalytic decomposition product and the second photocatalytic decomposition product in the first stream of material is 3-25:1; The second stream of materials consists of tetrabromobisphenol A, alkaline compound, end-capping agent, deionized water and organic solvent; The mass ratio of the first material to the second material in the mixed solution is 753-971:1578-1638.

9. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 8, characterized in that: The alkaline compound is one of the following: sodium hydroxide, potassium hydroxide, aluminum hydroxide, ammonia water, potassium methoxide; The end-capping agent is phenol; The organic solvent is carbon tetrachloride or toluene; The weight ratio of tetrabromobisphenol A, alkaline compound, end-capping agent, deionized water and organic solvent in the second stream of material is 333:65:20-80:580:

580.

10. The environmentally friendly production method for continuously producing brominated polycarbonate according to claim 2, characterized in that: During the purification, the washing and purification temperature is controlled to be 20-25°C, and the material residence time is 1-10min; The washing liquid is at least one of the following: deionized water, methanol, acetone; The volume ratio of the washing liquid to the polymerization product is 1:1-5.

Images